Applicants are now aware of any prior art reference which, in their respective judgments as one skilled in the prostaglandin art, would anticipate or render obvious the novel compounds of the instant invention; however, for the purpose of fully developing the background of the invention and establishing the state of the requisite art, the following references are set forth: U.S. Pat. No. 3,884,969; Japanese Pat. No. 3,884,969; German Offen. No. 2,515,770; German Offen. No. 2,510,818; and Netherlands published Patent Application No. 7,410-185.